I have a Macbook Pro 15" 2018 running High Sierra and I installed Windows 10 using bootcamp. I had duet display installed on both HS and Win10, and I installed Parallels Desktop 14 on the MacOS side and had it run the bootcamp partition instead of installing a new instance of win10. I think duet display caused some problems because the MacOS version was trying to mirror with the ipad at the same as the Win10 duet display running duet display (that was dumb, I know. it was a careless accident). It crashed/stalled and I couldn't shut down or suspend win10 in Parallels. I ended up force quitting Parallels using activity monitor. Now I can't boot into windows by holding option on bootup. However, I do have the Paragon NTFS for Mac that allows me to view NTFS partitions and all my data is on there and now backed up. I'd rather not have to reinstall everything if all it takes is fiddling with the EFI partition. Any ideas?
OK, since I can read the bootcamp partition, I guess I'll just back it up and reinstall Windows. I'll first have to manually delete the bootcamp partition and resize the MacOS partition manually, since Bootcamp assistant doesn't know what to do now (fairly useless app, in my opinion!).
Thanks for everyone's input.